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Author Topic: Does P-T lose bottom when you transfer from tape? Testing Mixerman's premise  (Read 22789 times)

Offline maccool

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Fletcher wrote on Tue, 01 November 2005 00:29

Whether or not MM agrees to the test methodology is a moot point

Je m'en doubte.  But, we shall see.  Go for it Fletch, I await the results with breath abated.
"Live sound will always be different."  Paul Frindle

Offline J.J. Blair

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Re: The big Transfer/ Summimg comparison Test Thread.
« Reply #46 on: October 31, 2005, 08:13:36 pm »
Christ, I haven't even read through any of this yet, and I already have a problem with the proposed concept.  Why compare it to 2" at all, especially for low end response?  Different machines have different low end responses at different tape speeds.  Why not just run white and pink noise into an HD rig and then analyze the frequency response?  Depending on the tape speed, 2" will tend to give you a head bump at either 50hz or 100hz.  Of course HD will sound like it has a less 50hz!
studio info

They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

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Offline Bob Olhsson

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Re: The big Transfer/ Summimg comparison Test Thread.
« Reply #47 on: October 31, 2005, 09:58:33 pm »
J.J. Blair wrote on Mon, 31 October 2005 19:13

...Why not just run white and pink noise into an HD rig and then analyze the frequency response?
Because it won't tell you what's happening dynamically. The designers generally get THAT part right.

Offline Ron Steele

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When I first talked to CRC about this and mentioned the fact that someone claimed that Digi HD192 was missing th 50 hz, they said "no way".  According to their test equipment { the scientific kind you see a tech use when he's fixing shit }  HD is flat as a door.

I will find out what sci-fi test gear they have. I know there tech department is a very serious one as they are involved in serious post production as well.
http://www.chicagorecording.com/newcrc/index.htm
 "I have had PLENTY of my posts torched on other boards. It kind of goes with the territory of pushing the envelope. Their house, their rules. Why can't everyone GET this?"

Offline J.J. Blair

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Bob, I see your point.  Still, I think comparing against 2" to measure the low end response is a misguided idea.
studio info

They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

Offline Bob Olhsson

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He wasn't comparing against 2" he was comparing the sound of 2" with the sound of a Pro Tools transfer from the same 2"..

I've heard the sound of a live drum kit from an MCI console back to back with hearing it played back from ProTools HD. It sounded exactly like mixerman described, the "balls" were missing.

Offline J.J. Blair

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Oops.  I misunderstood (again)!
studio info

They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

Offline blairl

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Bob Olhsson wrote on Mon, 31 October 2005 21:54

I've heard the sound of a live drum kit from an MCI console back to back with hearing it played back from ProTools HD. It sounded exactly like mixerman described, the "balls" were missing.


Do you think there is anything to be done to avoid this kind of problem?  What factors caused what you were hearing in your opinion?

Offline malice

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blairl wrote on Tue, 01 November 2005 07:33

Bob Olhsson wrote on Mon, 31 October 2005 21:54

I've heard the sound of a live drum kit from an MCI console back to back with hearing it played back from ProTools HD. It sounded exactly like mixerman described, the "balls" were missing.


Do you think there is anything to be done to avoid this kind of problem?  What factors caused what you were hearing in your opinion?


Bob, I take the liberty of bringing back you theories from the MARSH, you cannot be everywhere at the same time all the time Wink

Bob Olhsson wrote on Sun, 30 October 2005 15:16

Maybe I should explain this a bit more.

The problem is one of dynamic headroom when operated at +4 average levels. In the case of the 888, switching the unit to "-10" doesn't help because it just inserts a pad. The degree of the problem depends on the device the 888 or hd box is feeding. Worst case is often a 10k or lower console input. Best case is a high impedance tube "grid" input.
ac
There are a number of workarounds but they are all a pain in the ass (or the pocketbook.) Ten dB. lower record levels is one. Turning the trim pots down all the way is another. The problem is that most real pro gear and tape machines were designed around operating at +4 average levels so you end up having to rework the entire gain structure of your studio. Even then, in the case of the 888, the lower levels reveal lots of RFI and "birdies" in the unit. The best work-around is third-party converters that operate more gracefully at plus 4.

Some gear has always had this problem however older studios had a shop where equipment was modified to solve such problems. It was not uncommon for high-end studios (and touring sound companies) to completely rework or replace the power supplies of commercial gear.


malice

Offline malice

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I think also that is is important to notice that this is not only Mixerman that experimented this. Myself, Bob, Slippermann, maybe Fletcher (not sure) have experienced the same phenomena.

If the explanation Bob gave us is right, it is not something you would measure with test tones like this.

I am saying this to cut the necessaries little conflicts that would cloud the experiment. We should act like adults and build our discussion with the hypothesis that everyone can have contributed to the discussion in good faith.

Need to be said one last time

malice

Offline compasspnt

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Looks like there is no need for a test at all.  The results are already in.

Offline CWHumphrey

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compasspnt wrote on Tue, 01 November 2005 07:09

Looks like there is no need for a test at all.  The results are already in.


Why not stream this up on the 'net in real time?  Then maybe we could lose all the "spin doctors."

-Carter
Carter William Humphrey

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"Or you can just have Carter do the recording, because he's Humphrey."-J.J. Blair

Offline blairl

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malice wrote on Mon, 31 October 2005 23:51

Bob, I take the liberty of bringing back you theories from the MARSH, you cannot be everywhere at the same time all the time Wink


Bob's description mentions the 888.  Was this a misprint?  I am interested in Bob's opinion on how this all relates to Pro Tools HD and the more commonly used 192 I|O.

Offline Mixerman

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I haven't bothered reading this thread yet, but I would like to point out one thing. When I stated 3 years ago, that there was a 6db roll off at 60 hz, I was trying to give some kind of picture as to the severity of the problem. That is not a measurement that I have made. I would say that the most accurate description of the problem is the lopping off of the bottom octave. If you are in an accurate listening environment, the low end energy loss is quite apparent when compared to the original 2".

As I have stated many times, this is a glaring problem. I do not expect the HD unit to sound exactly like the 2". I do however expect it to be relatively close. When I make the same transfer into a RADAR and compare, while I still prefer the opriginal 2" for obvious reasons, the differences are negligible and I am able to move on without feeling that the integrity of my audio was destroyed.

That's all.

Carry on.

Mixerman
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Offline j.hall

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so my question is, if you are running the 2" deck at 30 ips, it will naturally start rolling off at 50Hz (the bottom octave)

so this 6dB down at an estimated 50 - 60Hz, is that above and beyond what the tape deck is already doing?

i guess i'm confused at how PT HD can "lop off" the bottom octave when the tape deck is already doing just that.